Contributors MBE designed the study, with collaboration of the coauthors as described below, and was largely responsible for the writing
of the manuscript. BE designed the parent study, directed data collection and contributed to the study design and editing
of the manuscript. EAB helped to design the study's analytic strategy, ran the statistical analyses and contributed to the
interpretation of the data and the writing of the Methods and Results sections. ROW and RJW contributed to the study design
and writing of the Introduction and Discussion sections. Each of the authors has reviewed the manuscript and made edits as
appropriate. MBE, BE and EAB had access to the data presented in the manuscript and take responsibility for the integrity
of the data and accuracy of the data analyses. There are no other individuals who fulfil the criteria for authorship.

Accepted 31 January 2012

Published Online First 4 April 2012

Abstract

Background Childhood trauma exposure has been associated with deficits in cognitive functioning. The influence of timing of exposure
on the magnitude and persistence of deficits is not well understood. The impact of exposure in early development has been
especially under-investigated. This study examined the impact of interpersonal trauma exposure (IPT) in the first years of
life on childhood cognitive functioning.

Results IPT was significantly associated with decreased cognitive scores at all time points, even after controlling for socio-demographic
factors, maternal IQ, birth complications, birth weight and cognitive stimulation in the home. IPT in the first 2 years appeared
to be especially detrimental. On average, compared with children not exposed to IPT in the first 2 years, exposed children
scored one-half SD lower across cognitive assessments.

Conclusion IPT in early life may have adverse effects on cognitive development. IPT during the first 2 years may have particular impact,
with effects persisting at least into later childhood.

Footnotes

Funding The research was supported by grants to BE from the Maternal and Child Health Service (MCR-270416), the William T Grant Foundation,
New York, and the National Institute of Mental Health (MH-40864). During preparation of this manuscript, the authors were
supported by K08MH074588 (MBE), R01HD054850 (BE), R01ES013744 (ROW) and R01 MD006086 (RJW). The content is solely the responsibility
of the authors and does not necessarily represent the official views of the National Institutes of Health.